Triglycerols

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Triglycerols (also called triglycerides, triacylglycerols, TAG, TG or triacyleglycerides) are the product of three fatty acids reacting with a glycerol molecule in an esterification reaction; this therefore makes triglycerols esters and are also referred to as hydrolysable lipids (they can dissolve in organic solvents). They are the main components of body fats in most animals as well as in human beings and they can be both obtained from our diet and made naturally in our body. Occurring in the blood. they provide energy to cells and and allow the bidirectional transference of adipose fat and blood glucose from the liver[1].

Although there are a wide variety of triglyerols, the main types include unsaturated where there is at least one double bond present in the chemical structure and saturated where there are no double bonds (only single bonds) thereby enabling all possible bonds between hydrogen atoms and carbon atoms to take place and form (here the molecule is said to be "saturated" with hydrogen). Saturated triglycerols tend to have higher melting points than unsaturated triglycerols, as a result they are usually solid at 298 K (room temperature) for example butter, whereas unsaturated triglycerols tend to be liquid at this temperature for example vegetable oils[2].

Triglycerols form when all three -OH (hydroxyl) groups of a glycerol molecule combine with the -COOH (carboxyl) group of three fatty acids (these can be the same or different in structure) thereby forming 3 esters bonds with the products being an ester and 3 water molecules being released. This reaction is called esterification as an ester is formed as the end-product, however because at least one water molecule is being released it can also be called a condensation reaction. If all three fatty acids have the same chemical structure (i.e. the same R groups), then we have a simple triglycerol however if all three fatty acids are not the same then we have a mixed triglycerol.

Referencing

  1. Jessie Szalay, Live Science Contributor, Live Science, 2016, March 24, https://www.livescience.com/54151-triglycerides.html
  2. Revision World, Lipids, ND, 03/21/17, https://revisionworld.com/a2-level-level-revision/biology/biological-molecules/lipids
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